Drum pulleys and wing pulleys used to drive conveyor belts or similar devices are normally provided with high friction surfaces for increased traction between the pulley and belt. The high friction surfaces are usually strips, or pads of rubber, in the form of laggings. In the past rubber laggings were either permanently affixed or rigidly secured to the pulley perimeter; however, this proved to be impractical due to the frictional wear and deterioration of the rubber over an extended period of time. The difficulty of removing the friction surfaces from the pulleys when the material was worn down led to the development of replaceable lagging structures. Examples of such replaceable laggings may be had by reference to U.S. Pat. Nos. 3,363,476; 3,354,735; 3,392,594; 3,046,805 and 3,220,272.
While all of the prior art devices enumerated above perform reasonably well on the specific type of pulley for which they are designed, they are not interchangeable between the drum and wing pulleys. Another problem encountered is that there is no uniformity with respect to lagging sizes and dimensions among specific and individual types of pulleys. A quick review of the patents listed supra, would confirm that none of the lagging structures employed for the wing pulleys, could be readily substituted for one another. This problem is not restricted to the wing pulleys, as the same situation applies to the drum pulleys as well.
As a consequence of this lack of uniformity, suppliers of laggings are required to keep an enormous inventory, on hand, and in stock, of a variety of sizes, configurations and types of replaceable laggings to satisfy their customers tailored needs.
A universal lagging structure which solves this problem is embodied in the invention which forms the basis for this application.